Is the SPG O-ring supposed to be replaced during annual inspections?

[halocline]

Only qualified techs should service stuff and use only OEM parts doing so.

How do you define "qualified?" How do you know what "OEM" o-rings are? What if you found out that OEM o-rings on your SPG spool were not 90 duro viton, like you say you use? I've taken apart lots of SPG spools with original o-rings, and although it's a little more difficult to tell because the o-rings are so small, I would be willing to bet that most of them were not 90 duro.

 

[redacted]

I favor EPDM but still have the more expensive Viton in my stock. I have some in Duro 90 (Viton) but have never had any problems with Duro70/75 in that application. Apparently the spool is pretty tight so there is little room for extrusion. With the lower hardness, It is pretty easy to lube them and "stab" them onto the spool. I have made quite a few repairs on those o-rings (other diver's regs) in the field and I don't carry many tools.

 

[miketsp]

These o-rings last a long time.
..snip..

They might just last a long time if you rarely swivel your SPG while pressurized and if you rinse well after each usage but it's worth noting that if you have one of those triple consoles with the compass on the rear face and you are constantly rotating the unit during all your dives, you might not even get 6 months of life.

So I expect to have this o-ring changed at any service AND I got into the habit of always carrying spares even though I now have a wrist mounted compass.

 

[fppf]

Every now and then you need a little disclaimer
"Qualified" means someone with proper training in the field in question.

I'm aware that mfgrs are using shore 70A orings in some high pressure seals. I would always recommend using what ever the original mfgrs tells you or sells you. That said, I also have taken apart a fair share of stuff to find orings starting to extrude out.

If you pull up that manual and jump to page 3-3, figure 3-2 you will see a rough guide line for hardness, clearance gap, and pressure. Note a shore 70A oring with 3,000 PSI needs a zero clearance. Shore 90 is good to about 3500 PSI with about 0.005" clearance.

I also use Grainger because I have a local store near me and if I have the items delivered there I don't pay shipping and I normally get stuff within 1-2 days of ordering.

 

[LeadTurn_SD]

fppf: Thanks for posting the link to the Parker o-ring literature!


Scubagolf: A good shop will at least inspect the SPG spool o-rings at time of service. What I do for my own regs is clean, inspect, relube "in-place" if they look good... and change them every other service.

Best wishes

 

[aquaregia]

My LDS does the SPG with the regs.

 

[Zung]

They might just last a long time if you rarely swivel your SPG while pressurized and if you rinse well after each usage but it's worth noting that if you have one of those triple consoles with the compass on the rear face and you are constantly rotating the unit during all your dives, you might not even get 6 months of life.

So I expect to have this o-ring changed at any service AND I got into the habit of always carrying spares even though I now have a wrist mounted compass.

It's true that we rarely if ever at all play with the hardware while we dive. I'd look at the SPG once before the dive to make sure there's air, mabe give it a 1/4 turn to adjust the view angle, and a few times after about 1/2 hour to an hour depending on the depth to make sure there's still air left. We do have hose mounted compasses, but I prefer to find my way back by watching the "skyline".

It's good information you give, I'll do it every other service or so, but now I have to start shopping for those little guys.

 

[Mr Carcharodon]

It seems to me the spool o-rings are a bit of red herring. At least with the spools I have worked with contamination from the spool corroding is a bigger issue than the o-rings going bad. Given the design of the hose end a long soak in fresh water is about the best you can do to get the salt water out of there for routine maintenance. But there likely will be some trapped salt water and corrosion that develops over time. As usual the solution is to clean the spool in a detergent/vinegar solution with a ultrasonic cleaner. If you have everything apart you might as well replace they o-rings. Also really you should clean the hose end too, and blow it dry. There is more involved to maintaining the SPG than just the o-rings.

 

[fppf]

It seems to me the spool o-rings are a bit of red herring. At least with the spools I have worked with contamination from the spool corroding is a bigger issue than the o-rings going bad. Given the design of the hose end a long soak in fresh water is about the best you can do to get the salt water out of there for routine maintenance. But there likely will be some trapped salt water and corrosion that develops over time. As usual the solution is to clean the spool in a detergent/vinegar solution with a ultrasonic cleaner. If you have everything apart you might as well replace they o-rings. Also really you should clean the hose end too, and blow it dry. There is more involved to maintaining the SPG than just the o-rings.

Very very true, corrosion is a huge issue with orings. It hurts two ways, one it creates a rough surface that chews up the oring, second the rough surface creates leak paths the oring can't seal. I have asked may manufactures why they still use chrome plated brass when there are so many better materials these days. This is not the 60's anymore.

I don't think Soaking a reg really does anything. The pressure at depth drives the saltwater into the crevices where it just sits. Soaking just wont penitrate into the crevisives and get the salt out. It is also an issue with the LP hose connection to the second stage.

 

[PhilEllis]

I have talked with many scuba technicians, and very few admit to including the HP spool o-rings in a typical service.

In our store, we offer two different "products" for regulators.

We have an "inspect and adjust" service where we visually inspect the complete regulator set, check/adjust the intermediate pressure, adjust the cracking effort, and fully test the regulator on an atmospheric flow bench. WITH REGARD TO THE HP SPOOL, with this service we simply submerge the pressure gauge/console and watch for leaks while we manipulate the gauge.

For our "rebuild service", we disassemble the entire regulator, properly clean all components, and replace all soft parts and o-rings. For this service, we always replace the entire hp spool assembly, which comes complete with o-rings already installed.

It is my opinion that the HP spool is likely the most fragile part of a regulator system. The spool is a cheaply made part, has extremely thin wall thicknesses, and is exposed to pretty extreme side loads in typical diving conditions. I personally try to avoid replacing those little o-rings whenever possible. It is simply too easy and too inexpensive to replace the entire spool.

Phil Ellis
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